My 3 (soon to be 4) year old daughter is still crying

My daughter has been going to the same daycare since Sept 2009.  My husband takes her there most mornings and then I usually pick her up.  Every morning that she goes (3-4 times a week) it is the same thing, she cries all the way there (5 miles) and then continues to cry for another 15-30 minutes.  Now even the day care kids are trying to console her.  But it has been every day for the past 10 months.  Some days she  even cries after nap time.  Today the daycare told me that my daughter has not been playing with the children for the past month, more solitary play.  That makes me nervous.
This is my first and to be only child and I do not know what more i can do.  I have talked to other family members and friends about this and talked with the new doctor, but all they say is that it can be that age and also being an only child it is more common and not to worry.  Well I am and we have talked the talk about work, school play and we are going to pick her up after snack time and movie time.  But it is not working.  What more can I do.

[jdtm]

This is called separation anxiety.  I might suggest you google the phrase "anxiety and children" or "separation anxiety and children" or "separaton anxiety disorder in children" or similar words/phrases.  Educate yourself and then contact your pediatrician for additional advice.  Ten months is too long of a time for this behaviour to be a phase or stage.  Ask your doctor for a referral to a medical mental health specialist as a child neurologist or child psychiatrist or someone with experience in anxiety disorders for treatment advice.  Often, a plan of parental intervention is all that is required for a child this young, but you will require help in devising this plan (as all children are different).  Your daughter will need help in order to learn how to manage her fears/anxieties.  Good luck ....